Add regexp matching for route to element transformers

[bostrom]

As one possible solution to #1289 (but also as a useful feature in itself), I added regexp matching for the route parameter in addElementTransformer.

If the route is given as a regexp /route/ to addElementTransformer, then the transformer function is stored in a separate transformers array along with its "matcher". When transforming elements, the regexp transformer array is first iterated to check which transformers match the current route and execute those. After that, it goes on as normal.

[bostrom]

As a side not, I couldn't get the tests to run on PhantomJS. I got this error:

Running "karma:build" (karma) task
17 10 2016 17:10:51.639:INFO [karma]: Karma v0.13.22 server started at http://localhost:9876/
17 10 2016 17:10:51.650:INFO [launcher]: Starting browser PhantomJS
17 10 2016 17:10:53.601:INFO [PhantomJS 1.9.8 (Mac OS X 0.0.0)]: Connected on socket XhNbgIpgJQtwpb7vAAAA with id 65452568
PhantomJS 1.9.8 (Mac OS X 0.0.0) ERROR
  TypeError: 'undefined' is not an object (evaluating 'angular.module')
  at /Users/bostrom/Projects/restangular/src/restangular.js:13

Seems that angular isn't loaded on the window object when restangular is loaded...